The World Health Organisation recently released its most detailed study on global pollution to date and the results are, no pun intended, breath taking: over 90% of the population lives in places where air pollution exceeds safe limits. Three million people are reportedly dying every year as a result of tiny particulates in the air – solid and liquid matter that is suspended in the air we breathe, and arrives there from a wide range of human-made sources, from car fumes and power plants. Long term exposure to these particulates is linked to a number of respiratory illnesses. Given the demonstrable effect on humans, how, we might ask, does it affect birds?

In 2013, birds started falling from the skies in Singapore because of smog that had formed as a result of forest fires. Multiple studies have shown that birds respond to environmental change before humans can even notice it. This is why birds are invaluable indicators of the health of our environment. Everyone who is familiar with the story of the canary in the coal mine will know that when birds begin to disappear there’s something nasty in the air.

Pollution of many types has been reported to impact negatively on birds. We are all familiar with the effects of oil spills, plastic litter, pesticides and other water-borne pollutants that can easily wreak havoc in wetlands and coastal habitats. However when it comes to invisible airborne pollutants, the effects are more difficult to trace back.

But what can be easily traced back is rainfall and its effect on the environment. Air pollution is not only about the air we breathe. Toxic fumes coming from cars, domestic heating, power plants, factories and agriculture all pollute the atmosphere with sulphur and nitrogen compounds. After travelling for long distances, these compounds fall as acid rain, which has been implicated in population declines of several bird species in industrialised countries like the USA and UK. Even when clean air laws are in place, as in the eastern regions of North America, acid rain is still an issue that has been linked to population declines of threatened species such as Bicknell’s Thrush Catharus bicknelli.

In its conclusions, WHO proposes a range of solutions to tackle the air pollution crisis: sustainable transport, improved waste management and increasing use of renewable energies. This new study reminds us that most of the sources that cause air pollution happen also to be drivers of climate change – a threat identified as a priority by BirdLife International. This is where our solutions for nature come in handy. Our top recommendation to tackle climate change also happens to improve air quality for people and for birds; keep fossil fuels in the ground and ensure the transition to renewable sources happens as quickly as possible.

Following the UK Clean Air Act of 1956, several species of birds that had disappeared from the city of London were reported to have returned, from Common Hoopoe Upupa epops to Bohemian Waxwing Bombycilla garrulus. This goes to show that it’s never too late to clean up the mess: when the air is fit to breathe again, birds will be the first to let us know.